1. Field of the Invention
The present invention relates to devices for testing shaft bearings in a high vacuum chamber.
2. The Prior Art
Bearings must withstand high thermal loadings and operate under high vacuum conditions in various applications.
It is well known to test materials and devices of the most varied kinds under such "environmental conditions". It is known to operate ball bearings under load in high vacuum chambers in a pressure range extending from 10.sup.-3 to 10.sup.-11 mm.Hg. Cooling of the high vacuum chambers is carried out using liquid nitrogen or helium.
One known device for testing shaft bearings consists of a substantially cuboid high vacuum chamber in which a shaft carrying the test bearing is rotatably assembled and driven by an electric motor with a field winding arranged outside the chamber. A heating system for the test bearing is provided. An axial load may be applied to the test bearing by a test load arranged inside the high vacuum chamber. The chamber is equipped with an inspection glass for observation therethrough of the test bearing during testing.
In such known high vacuum chambers, test loads cannot be varied during the test. Also, the test bearing cannot be radially loaded.
For proper testing of a bearing, it is necessary for both radial and axial loads to be variable in magnitude during the conduct of the test; also, the smoothness of running of the bearing during test operation must be observable and recordable. If the bearing is to be run while subject to a thermal load, bearing heat must be dissipated from the high vacuum chamber.